That will all be explained in detail in class. Additionally you'll be shown options to buy gear. Most shops have their best chance to sell you gear before/during and just after certification.
I suggest that the only thing you buy right now is the required mask/fins/boots/snorkel - the shop will provide/rent you the rest. When buying a mask - the single most important thing is FIT. Not style, fancy silicon materials, used, adjustable straps etc. Esp. in local water, you'll be miserable when the mask leaks 60o water onto your face. It can also be such a shock as to be a problem requiring you to abort the dive - or worse. Maui not so much...lol.
If it's a good shop, they'll have your best interests at heart when making gear suggestions. If it's not, they'll push whatever they currently have too much of/make the best margins on. It's important to know/realize the differences. Best is not always most expensive either - scuba is littered with a history of expensive failures - dive mfr's are always trying to entice everyone to buy the latest/greatest so add useless/unneccessary bling. Which often breaks. I can't for the life of me understand how they think plastic is a good idea for dive gear that carries a heavy metal tank, is in corrosive water and spends a lot of it's life being bleached by the sun.
Another factor to consider is type of gear. Something optimal for PNW diving is going to be very different than lighter weight gear sold for diving in the Caribbean. Some gear can do both with modification. There's also some basic considerations. Shops generally have Jacket style rental BC's, they're typically available as shop rentals at a lower cost. They're easiest for the shops since they just put you in the appropriate size and add weight. They work, many people actually go on to buy better versions since they learned in one. IMO (just mine) the best thing a Jacket BC does is float you high/vertical at the surface. If all my diving was there, I might own one. The other two styles of BC, Back-inflate or Backplate/Wing have all the buoyancy on your back. So that any air trapped in the wing is above you - makes it easier to trim out horizontally which is how most people dive. A BP/W has evovled from technical diving - more of a minimalist configuration allowing for precise control - important in cave/wreck diving where silting the area out can be a big problem.
People I know who dive in the PNW use BP/W's for recreational dives also since they get some weight off by design. Since you'll likely be wearing layers of wetsuit, which floats, you'll need a lot more weight to compensate for it than in the tropics. On the flip side if you only dive in the tropics, there is a range of lighter weight gear available. Some is so flexible you roll it up and it will fit in a carry-on.
Ask about anything you're considering here. Someone is/has likely used just about everything available.
I realize being excited it seems like buying all new gear now is a good idea. I thought so also. A year later I sold just about everything I owned and bought what I really needed. Read the forums here, it repeats itself thousands of times a year.
I'm not a fan of buying used but there can be some very good gear available here in our classifieds, on eBay or Craigslist. Buying gear from someone here you have a reasonable chance of it being properly represented, we'll name/shame anyone that doesn't. I see a lot of old junk on eBay for ridiculous prices - IMO craiglist is at least as bad - there you get the estate sales or people who last dove their gear 10 years ago and still think it's worth 80% of what they paid. Personally in the past I won a $750 regulator. Since mine are better I sold it to a guy here for $600 - new in the box with warranty card intact. We also frequently have shops offer excess gear here - in addition to our Sponsors deals - most of whom also own dive related businesses.
Quick example, a member here just asked me about an integrated octo 2nd stage he found online. Almost brand new. For $200 - $60 less than what it's currently selling for. But I pointed out that it didn't include the hoses. One is proprietary and retails around $70 - $95 from the dealer. The other is a standard $20 hose. So $290-315 used vs. $260 new?
